Android:Drag n Drop List View

public class DndListView extends ListView {
 private Context mContext;
 private ImageView mDragView;
 private WindowManager mWindowManager;
 private WindowManager.LayoutParams mWindowParams;
 private int mDragPos;
 private int mFirstDragPos;
 private int mDragPoint;
 private int mCoordOffset;
 private DragListener mDragListener;
 private DropListener mDropListener;
 private int mUpperBound;
 private int mLowerBound;
 private int mHeight;
 private Rect mTempRect = new Rect();
 private Bitmap mDragBitmap;
 private final int mTouchSlop;
 private int mItemHeightNormal;
 private int mItemHeightExpanded;
 private int dndViewId;
 private int dragImageX = 0;
 private int totalchilds = 0;
 
 public DndListView(Context context, AttributeSet attrs) {
  super(context, attrs);
  mContext = context;
  mTouchSlop = ViewConfiguration.get(context).getScaledWindowTouchSlop();// etScaledTouchSlop();
  totalchilds = getChildCount();
 }
 
 @Override
 public boolean onInterceptTouchEvent(MotionEvent ev) {
//  Logger.debugE(“DndListView Intercept :” + ev.getAction());
 
  if (getChildCount() > 0)
   totalchilds = getChildCount();
 
  if (mDragListener != null || mDropListener != null) {
   switch (ev.getAction()) {
   case MotionEvent.ACTION_DOWN:
    int x = (int) ev.getX();
    int y = (int) ev.getY();
 
    if (x < this.getWidth() – 50) {
     return false;
    }
 
    int itemnum = pointToPosition(x, y);
    System.out.println(“Item num :” + itemnum);
    if (itemnum == AdapterView.INVALID_POSITION) {
     break;
    }
    View item = (View) getChildAt(itemnum
      - getFirstVisiblePosition());
    // item.setBackgroundColor(Color.RED);
    mItemHeightNormal = item.getHeight();
    mItemHeightExpanded = mItemHeightNormal * 2;
    mDragPoint = y – item.getTop();
    mCoordOffset = ((int) ev.getRawY()) – y;
    View dragger = item.findViewById(dndViewId);
    if (dragger == null)
     dragger = item;
    Rect r = mTempRect;
    dragger.getDrawingRect(r);
    if (x < r.right * 2) {
     item.setDrawingCacheEnabled(true);
 
     Bitmap bitmap = Bitmap.createBitmap(item.getDrawingCache());
     startDragging(bitmap, y);
     mDragPos = itemnum;
     mFirstDragPos = mDragPos;
     mHeight = getHeight();
 
     int touchSlop = mTouchSlop;
     mUpperBound = Math.min(y – touchSlop, mHeight / 3);
     mLowerBound = Math.max(y + touchSlop, mHeight * 2 / 3);
     return false;
    }
    mDragView = null;
    break;
   }
  }
  return super.onInterceptTouchEvent(ev);
 }
 
 public void redraw(int pos) {
  for (int i = 0; i < getChildCount(); i++) {    View v = getChildAt(i);    if (i == pos)     v.setBackgroundColor(Color.parseColor(“#E0E0E0″));    else     v.setBackgroundColor(Color.WHITE);   }  }  public void refresh() {   long time = Long.parseLong((“” + System.nanoTime()).substring(0, 7));   MotionEvent me = MotionEvent.obtain(time, time,     MotionEvent.ACTION_DOWN, getWidth() – 10, 300, 0);   onInterceptTouchEvent(me);   stopDragging();  }  @Override  public boolean onTouchEvent(MotionEvent ev) {   if (getChildCount() > 0)
   totalchilds = getChildCount();
 
  if ((mDragListener != null || mDropListener != null)
    && mDragView != null) {
   int action = ev.getAction();
   switch (action) {
   case MotionEvent.ACTION_UP:
   case MotionEvent.ACTION_CANCEL:
    Rect r = mTempRect;
    mDragView.getDrawingRect(r);
    stopDragging();
    int y = (int) ev.getY();
    int speed = 0;
    if (mDropListener != null && mDragPos >= 0
      && mDragPos < getCount()) {
     mDropListener.drop(mFirstDragPos, mDragPos);
 
     if (mDragPos < (totalchilds-1) )
      setSelectionFromTop(0, 0);
    }
    unExpandViews(false);
    break;
 
   case MotionEvent.ACTION_DOWN:
   case MotionEvent.ACTION_MOVE:
    int x = (int) ev.getX();
    y = (int) ev.getY();
 
    if (x < this.getWidth() – 50) {      return false;     }     dragView(x, y);     int itemnum = getItemForPosition(y);     if (itemnum >= 0) {
     if (action == MotionEvent.ACTION_DOWN
       || itemnum != mDragPos) {
      if (mDragListener != null) {
       mDragListener.drag(mDragPos, itemnum);
      }
      mDragPos = itemnum;
      doExpansion();
     }
     speed = 0;
     adjustScrollBounds(y);
     if (y > mLowerBound) {
 
      speed = y > (mHeight + mLowerBound) / 2 ? 16 : 4;
     } else if (y < mUpperBound) {
 
      speed = y < mUpperBound / 2 ? -16 : -4;      }      if (speed != 0) {       int ref = pointToPosition(0, mHeight / 2);       if (ref == AdapterView.INVALID_POSITION) {        // we hit a divider or an invisible view, check        // somewhere else        ref = pointToPosition(0, mHeight / 2          + getDividerHeight() + 64);       }       View v = getChildAt(ref – getFirstVisiblePosition());       if (v != null) {        int pos = v.getTop();        setSelectionFromTop(ref, pos – speed);       }      }     }     break;    }    return true;   }   return super.onTouchEvent(ev);  }  private int getItemForPosition(int y) {   int adjustedy = y – mDragPoint – 32;   int pos = myPointToPosition(0, adjustedy);   if (pos >= 0) {
   if (pos <= mFirstDragPos) {
    pos += 1;
   }
  } else if (adjustedy < 0) {    pos = 0;   }   return pos;  }  private int myPointToPosition(int x, int y) {   Rect frame = mTempRect;   final int count = getChildCount();   for (int i = count – 1; i >= 0; i–) {
   final View child = getChildAt(i);
   child.getHitRect(frame);
   if (frame.contains(x, y)) {
    return getFirstVisiblePosition() + i;
   }
  }
  return INVALID_POSITION;
 }
 
 private void adjustScrollBounds(int y) {
  if (y >= mHeight / 3) {
   mUpperBound = mHeight / 3;
  }
  if (y <= mHeight * 2 / 3) {    mLowerBound = mHeight * 2 / 3;   }  }  private void doExpansion() {   int childnum = mDragPos – getFirstVisiblePosition();   if (mDragPos > mFirstDragPos) {
   childnum++;
  }
 
  View first = getChildAt(mFirstDragPos – getFirstVisiblePosition());
  for (int i = 0;; i++) {
   View vv = getChildAt(i);
   if (vv == null) {
    break;
   }
   int height = mItemHeightNormal;
   int visibility = View.VISIBLE;
   if (vv.equals(first)) {
 
    if (mDragPos == mFirstDragPos) {
     visibility = View.INVISIBLE;
    } else {
     height = 1;
    }
   } else if (i == childnum) {
    System.out.print(“I :” + i);
    if (mDragPos < getCount() – 1) {
     height = mItemHeightExpanded;
    }
   }
   ViewGroup.LayoutParams params = vv.getLayoutParams();
   params.height = height;
   vv.setLayoutParams(params);
   vv.setVisibility(visibility);
  }
 }
 
 private void unExpandViews(boolean deletion) {
  for (int i = 0;; i++) {
   View v = getChildAt(i);
   if (v == null) {
    if (deletion) {
     int position = getFirstVisiblePosition();
     int y = getChildAt(0).getTop();
     setAdapter(getAdapter());
     setSelectionFromTop(position, y);
    }
    layoutChildren();
    v = getChildAt(i);
    if (v == null) {
     break;
    }
   }
   ViewGroup.LayoutParams params = v.getLayoutParams();
   params.height = mItemHeightNormal;
   v.setLayoutParams(params);
   v.setVisibility(View.VISIBLE);
  }
 }
 
 public void checkfordrop(int dragPos) {
  if (dragPos < totalchilds – 1)
   setSelectionFromTop(0, 0);
 }
 
 private void startDragging(Bitmap bm, int y) {
  stopDragging();
 
  mWindowParams = new WindowManager.LayoutParams();
  mWindowParams.gravity = Gravity.TOP;
  mWindowParams.x = dragImageX;
  mWindowParams.y = y – mDragPoint + mCoordOffset;
 
  mWindowParams.height = WindowManager.LayoutParams.WRAP_CONTENT;
  mWindowParams.width = WindowManager.LayoutParams.WRAP_CONTENT;
  mWindowParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
    | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE
    | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
    | WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN;
  mWindowParams.format = PixelFormat.TRANSLUCENT;
  mWindowParams.windowAnimations = 0;
 
  ImageView v = new ImageView(mContext);
  int backGroundColor = Color.parseColor(“#e0103010″);
  v.setBackgroundColor(backGroundColor);
  v.setImageBitmap(bm);
  mDragBitmap = bm;
 
  mWindowManager = (WindowManager) mContext.getSystemService(“window”);
  mWindowManager.addView(v, mWindowParams);
  mDragView = v;
 }
 
 private void dragView(int x, int y) {
  mWindowParams.y = y – mDragPoint + mCoordOffset;
  mWindowManager.updateViewLayout(mDragView, mWindowParams);
 }
 
 private void stopDragging() {
  if (mDragView != null) {
   WindowManager wm = (WindowManager) mContext
     .getSystemService(“window”);
   wm.removeView(mDragView);
   mDragView.setImageDrawable(null);
   mDragView = null;
  }
  if (mDragBitmap != null) {
   mDragBitmap.recycle();
   mDragBitmap = null;
  }
 }
 
 public void setDragListener(DragListener l) {
  mDragListener = l;
 }
 
 public void setDropListener(DropListener l) {
  mDropListener = l;
 }
 
 public void setDndView(int id) {
  dndViewId = id;
 }
 
 public void setDragImageX(int x) {
  dragImageX = x;
 }
 
 public interface DragListener {
  void drag(int from, int to);
 }
 
 public interface DropListener {
  void drop(int from, int to);
 }
}

 
public class ListDnD extends ListActivity implements DndListView.DragListener, DndListView.DropListener {
    /** Called when the activity is first created. */
 private DndListView lvList;
 private EfficientAdapter mAdapter;
 private boolean isDnd = false;
 private ArrayList list = new ArrayList();
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
 
        lvList = (DndListView) this.getListView();
 
        list.add(“http://www.wopll.com/“);
        list.add(“http://www.wopll.com/?p=368“);
        list.add(“http://www.wopll.com/?page_id=2“);
        list.add(“http://www.wopll.com/?feed=rss2“);
        list.add(“http://www.wopll.com/?cat=20“);
 
        mAdapter = new EfficientAdapter(this);
        setListAdapter(mAdapter);
 
        lvList.setDragListener(this);
  lvList.setDropListener(this);
    }
 
 private class EfficientAdapter extends BaseAdapter {
  private LayoutInflater mInflater;
 
 public EfficientAdapter(Context context) {
  mInflater = LayoutInflater.from(context);
 }
 public int getCount() {
  return list.size();
 }
 
 public Object getItem(int pos) {
  return pos;
 }
 
 public long getItemId(int pos) {
  return pos;
 }
 
 public View getView(final int pos, View convertView, ViewGroup parent) {
 
  ViewHolder holder;
 
  if (convertView == null) {
   convertView = mInflater.inflate(R.layout.simple_list_item_1, null);
   convertView.setBackgroundColor(Color.WHITE);
   holder = new ViewHolder();
   holder.item = (TextView) convertView.findViewById(android.R.id.text1);
   convertView.setTag(holder);
  } else {
   holder = (ViewHolder) convertView.getTag();
  }
  holder.item.setText(list.get(pos));
  return convertView;
 }
 
 class ViewHolder {
  TextView item;
 }
}
 
 @Override
 public void drag(int from, int to) {
  // TODO Auto-generated method stub
  if(!isDnd){
   isDnd = true;
   Log.i(“Drag and Drop : drag”, “from : ” + from + “, to : ” + to);
  }
 }
 @Override
 public void drop(int from, int to) {
  // TODO Auto-generated method stub
  if(isDnd){
   Log.i(“Drag and Drop : drop”, “from : ” + from + “, to : ” + to);
   if(from == to)
    return;
 
   String item = list.remove(from);
   list.add(to, item);
   isDnd = false;
 
   mAdapter.notifyDataSetChanged();
 
   lvList.checkfordrop(to);
  }
 }
}